Export Core Data into CSV in Swift 3

export.swift

   func createExportString() -> String {
        var name : String?
        var age : String?
        var mobile : String?
        var email : String?
        var promo_crayola_bunding : Int16?
        var promo_zip_it : Int16?
        var promo_none : Int16?
        var created : NSDate? = NSDate()
        
        var export : String = NSLocalizedString("Name, Age, Mobile, Email, Crayola Bunding, Zip It, None, Created Date \n", comment: "")
        for (index, census) in self.fetchAllCensus().enumerated() {
            name = census.name
            age = census.age
            mobile = census.mobile
            email = census.email
            promo_crayola_bunding = census.promo_crayola_building
            promo_zip_it = census.promo_zip_it
            promo_none = census.promo_none
            created = census.created
            
            let promoCrayolaBundingString = "\(promo_crayola_bunding)"
            let promoZipItString = "\(promo_zip_it)"
            let promoNoneString = "\(promo_none)"
            let createdDateString = "\(created!)"
            
            export += name + "," + age + "," + mobile + "," + email + "%,"
                + promoCrayolaBundingString + "," + promoZipItString + "," + promoNoneString + "," + createdDateString +  "\n"
        }
        
        return export
    }
    
   func saveAndExport(exportString: String) {
        let exportFilePath = NSTemporaryDirectory() + "export.csv"
        let exportFileURL = NSURL(fileURLWithPath: exportFilePath)
        FileManager.defaultManager.createFileAtPath(exportFilePath, contents: NSData() as Data, attributes: nil)
        var fileHandleError: NSError? = nil
        var fileHandle: FileHandle? = nil
        do {
            fileHandle = try FileHandle(forWritingToURL: exportFileURL)
        } catch {
            print("Error with fileHandle")
        }
        
        if fileHandle != nil {
            fileHandle!.seekToEndOfFile()
            let csvData = exportString.data(using: String.Encoding.utf8, allowLossyConversion: false)
            fileHandle!.writeData(csvData!)
            
            fileHandle!.closeFile()
            
            let firstActivityItem = NSURL(fileURLWithPath: exportFilePath)
            let activityViewController : UIActivityViewController = UIActivityViewController(
                activityItems: [firstActivityItem], applicationActivities: nil)
            
            activityViewController.excludedActivityTypes = [
                UIActivityType.assignToContact,
                UIActivityType.saveToCameraRoll,
                UIActivityType.postToFlickr,
                UIActivityType.postToVimeo,
                UIActivityType.postToTencentWeibo
            ]
            
            self.present(activityViewController, animated: true, completion: nil)
        }
    }

Very nice... quick question. How big/long can the 'exportString' be ? Can it hold infinite data? like 100000000 records ?

This will fail if any field contains "\n". ("name" = "A\nB\nC")